Stator for a multiple-pole dynamoelectric machine and method of fabricating same

ABSTRACT

A stator assembly for a multiple-pole (e.g., an 18 pole) induction motor has a main winding and an auxiliary winding, with the main and auxiliary windings each having a first and a second coil set, each of these coil sets having multiple coils selectively electrically connected together. The stator assembly further includes a core having slots for receiving the coils, which is continuously skein wound in an open, serpentine sequence. There is one coil of the first auxiliary winding coil set inserted in the first and third slots of the core, one coil of the first main winding coil set inserted in the second and fourth slots, one coil of the second auxiliary winding coil set inserted in the third and fifth slots, and one coil of the second main winding coil set inserted in the fourth and sixth slots thereby to form a layered coil insertion pattern of the coils in the first six slots of the core. Second coils from each of the coil sets are then inserted in a similar layered fashion in the slots 5-10 of the core to form another layered insertion pattern of the coils in the slots. This layered insertion pattern is repeated until all of the coils are inserted into the slots of the core. 
     A method of fabricating such a stator assembly for a multiple pole motor is also disclosed.

This is a division of application Ser. No. 315,288 filed Oct. 27, 1981filed Oct. 27, 1981 now U.S. Pat. No. 4,426,771.

BACKGROUND OF THE INVENTION

This invention relates to a method of fabricating a stator assembly fora multiple-pole dynamoelectric machine (e.g., an inductor motor) and toa stator assembly made in accordance with the method of this invention.

In certain electric motor applications, such as in ceiling fans, themotor is designed to run at a relatively low or slow speed. For example,a ceiling fan motor may be operated at 350 R.P.M. These motors may have18 poles, as compared to more conventional 2, 4, 6, or 8 pole motors.

Conventionally, the windings for these multiple-pole motors compriseconcentrically wound coil sets each having a plurality of separate,individual coils electrically interconnected with one another, one coilfor each pole of the motor. Thus, for an 18 pole motor, there would berequired 18 separate coils of magnet wire for the main winding of themotor and 18 separate coils of magnet wire for the auxiliary winding ofthe motor. Each of these individual coils typically had a large numberof turns of magnet wire. For example, each main winding coil of an 18pole ceiling fan motor may have 185 turns or more of No. 27-No. 30 wire.Because of the large number of turns and the large number of poles inthe motor, these 18 pole ceiling fan motors are difficult and expensiveto manufacture. Additionally, conventional coil winding and insertingtechiques utilized to manufacture these prior ceiling fan motors werelabor intensive and were thus expensive.

Typically, prior art concentrically wound coil set motors, such asillustrated in FIG. 4 of the drawings in the instant specification, havea plurality of coil (e.g., 18) of magnet wire electrically connected toone another and inserted in the slots of the core of the stator assemblyso as to form, for example, the main and auxiliary windings of themotor. Because of the high number of turns of wire in each of the coils,the end turns of the coils (i.e., the portions projecting out beyond theend faces of the stator core) are, of necessity, bulky and cannotreadily be formed into a tight radius. During operation of the motor,current must flow through the end turns of the windings, but the endturns do not serve to generate any substantial portion of the rotatingmagnetic field of the motor. Since the resistance losses of the motorare dependent primarily upon the length of the magnet wire contained inthe windings, it is desirable to make the end turns of the windings assmall as possible. Additionally, a considerable amount of copper magnetwire is consumed by the end turns which makes these prior art motorscostly.

Still further, because of the large end turns normally associated withsuch prior art concentrically wound coil, multiple pole motors, it wasnecessary to lace or tie the end turns of the auxiliary and mainwindings of the motor together with textile lacing material or the likethereby to hold the windings in place. This requirement of lacing theend turns was, of course, costly as it did require a substantial amountof labor and materials.

In an effort to reduce the size of the end turns, and yet to maintainthe same operating characteristics of the motor, a prior artconcentrically wound coil motor was developed in which the number ofcoils of the motor was doubled, but in which the number of turns percoil was halved. Further, the coils in this motor, as shown in FIG. 5,were split so that each pole for the main and auxiliary winding wasconstituted by a coil with the legs of adjacent coils sharing a commonslot. While this did somewhat reduce the size of the end turns and didresult in wire savings, it became a problem to wind such a large numberof coils, to transfer the coils from the winding apparatus to theinserting apparatus, and to insert them into the slots of the core. Thisfabrication process required a considerable amount of labor, was timeconsuming, and was therefore expensive.

Still further, it is known to skein wind the windings of an electricmotor. In a skein wound motor, the windings are formed by first windinga large coil or skein of magnet wire in the shape of a circle. Then, theskein is formed to be a petalled, serpentine shape having a plurality ofinner and outer apices (e.g., 9 inner apices and 9 outer apices) withstraight coil sections or legs extending between the apices. Such skinwound motor windings may be made on the apparatus and in accordance withthe method disclosed in the co-assigned U.S. patent application, Ser.No. 222,833, filed Jan. 6, 1981, invented by Vernon E. Kieffer. However,because these prior art skein windings were relatively thick and had amultiplicity of turns of magnet wire therein, they also had relativelylarge end turns.

SUMMARY OF THE INVENTION

Among the several objects and features of this invention may be notedthe provision of a stator for a multiple-pole dynamoelectric machine andthe method of fabricating such a stator, whether the windings of thestator are concentric wound or skein wound coils, in which the coils areinserted into the slots of the stator core so that the end turns of thecoils are reduced in size, resulting in substantial savings andfabrication cost, in substantial decreases in labor cost, and insubstantial increases in running efficiency for the motor;

The provision of such a stator and method which results in a windinginsertion scheme allowing the windings to be more easily inserted in thecore, to facilitate the manufacture of stators which could notheretofore readily be manufactured;

The provision of such a stator and method which reduces the amount ofend turn overlap, permitting a decrease in the length of the end turns;

The provision of such a stator and method which results in the coils ofthe windings being arranged in layered groups after insertion of thewindings of the core;

The provision of such a stator and a method which has a shorter end wire(or end turn) length;

The provision of such a stator and method which has sufficient room toreadily accommodate a thermal protector switch or lead connectionswithin the windings of the motor;

The provision of such a method and stator which eliminates therequirement of lacing the end turns of the windings of the motor; and

The provision of such a method and stator which may be used for singleor polyphase, full pitch motors.

Other objects and features of this invention will be in part apparentand in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a typicaldynamoelectric machine incorporting a stator assembly of the presentinvention;

FIG. 2 is an end elevational view of a stator assembly of the presentinvention illustrating the lapped arrangement of concentric coilsinserted in the stator slots of a core in accordance with the method ofthis invention;

FIG. 3 is a view similar to FIG. 2 illustrating another embodiment ofthe present invention utilizing skein wound coils inserted in the slotsof the stator core in an overlapping insertion pattern in accordancewith the method of this invention;

FIG. 4 is a view similar to FIG. 2 of a prior art concentric coil statorassembly;

FIG. 5 is a view similar to FIG. 4 of another prior art stator assembly;

FIG. 6 (sheet 5) is a view taken along line 6--6 of FIG. 2 illustrating,in a flat pattern layout, the arrangement of one coil set (e.g., a firstauxiliary winding coil set) with the straight coil sections or legs ofthis coil set inserted in a first group of core slots;

FIG. 7 is a view similar to FIG. 6 taken along line 7--7 of FIG. 3illustrating in flat pattern the arrangement of one coil set (e.g., afirst auxiliary winding coil set) of a skein wound coil set;

FIG. 8 is another view similar to FIG. 6, as described above, takenalong line 8--8 of FIG. 4 illustrating in flat pattern a prior artconcentric coil insertion pattern in a stator core;

FIG. 9 is a view similar to FIG. 6, as described above, taken along line9--9 of FIG. 5 illustrating in flat pattern another prior art concentriccoil insertion pattern in a stator core;

FIG. 10 is a semi-diagrammatic electrical connection diagram of the coilsets of the auxiliary and main winding coil sets of a motor in thisinvention, as shown in FIG. 2;

FIG. 11 is a view similar to FIG. 10 illustrating the electricalconnection diagram of the stator assembly of the present invention, asshown in FIG. 3;

FIG. 12 is a view similar to FIGS. 10 and 11, but illustrating theelectrical connection diagram of the prior art motor shown in FIG. 4;

FIG. 13 is a view similar to FIGS. 10-12, but illustrating theconnection diagram of a prior art concentric coil motor, as illustratedin FIG. 5;

FIG. 14 is a plan view of skein wound coil set for forming either themain or auxiliary winding of the motor shown in FIG. 3 of the presentinvention prior to the coil set's being inserted in the core slots;

FIG. 16 is a perspective view of a coil transfer tool holding aconcentric wound coil set for the embodiment of this invention shown inFIG. 2; and

FIG. 16 (sheet 2) is a side elevation view, shown partly in crosssection, of an axial coil insertion apparatus, such as shown in U.S.Pat. No. 3,748,714, used in accordance with this invention to insert thecoil sets in the core, the core being shown in phantom.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and particularly to FIG. 1, adynamoelectric machine is indicated in its entirety by referencecharacter 1. Specifically, this dynamoelectric machine is shown to be amultiple-pole induction motor having a stator assembly 3 of the presentinvention. This stator assembly consists of a core 5 made from a stackof suitable ferromagnetic laminations 7. Each lamination has a centralopening 9 therein (see FIG. 2) and a plurality of blind notches 11extending radially outwardly from the central opening. As best shown inFIGS. 2 and 3, these notches are substantially equally angularly spacedaround the lamination. When the laminations are stacked to form core 5and when the central openings 9 of the stacked laminations are arrangedcoaxially with the radial notches 11 in register with one another, thecentral openings of the stacked laminations form a bore B extendinglongitudinally through the core and the notches form slots S extendinglongitudinally through the core. The laminations are held in stacked,assembled position by means of cleats 12 or by other means well-known tothose skilled in the art. As shown in FIGS. 2-5, core 5 is provided with36 slots spaced at 10° intervals around the core. These slots arenumbered S1-S36, consecutively. Additionally, the portions of the statorcore between adjacent slots form stator teeth, these stator teeth beingconsecutively identified T1-T36.

Still referring to FIG. 1, motor 1 further includes a rotor assembly, asgenerally indicated at 13, comprising a rotor body 15, and a rotor shaft17 extending endwise from both ends of rotor body 15. The motor furtherincludes a shell 18 and bearing supports or end shields 19a, 19b securedto the ends of the shell and carrying bearings 21a, 21b which receiveand journal rotor shaft 17. As is conventional, an insulator 23 (seeFIG. 2) of suitable electrically insulative material of a typewell-known to those skilled in the art is inserted in each slot S1-S36of the stator core, to electrically insulate the windings W of the motorinserted in slots S1-S36. Additionally, after the windings have beeninserted in the stator slots, insulating wedges 25 may be inserted inthe open throats of the slots so as to close off the slots and tofurther insulate the windings and to prevent individual turns of thewinding from falling clear of the slots and possibly coming into contactwith rotor body 15 received in bore B.

Specifically referring to stator assembly 3, as shown in FIG. 2, core 5is shown to have a bore B of approximately 3.5 inches (8.9 cm.) andouter diameter of approximately 6.30 inches (16.0 cm.), and thirty sixslots S1-S36 spaced around bore B. Windings W of stator assembly 3 areof a type referred to generally as concentric coil windings and theyinclude an auxiliary winding A and a main winding M. Auxiliary winding Aincludes a first auxiliary winding coil set AC1 and a second auxiliarywinding coil set AC2. Main winding M includes a first main winding coilset MC1 and a second main winding coil set MC2. Each of these coil setsincludes nine coils C, each coil having a desired number of turns ofmagnet wire wound therein with each coil having a pair of opposed endturns (or apices) E (see FIG. 6) with straight coil sections or legs Lextending between and connecting the end turns of the coil. The magnetwire constituting each of the coils C is wound concentrically on itselfand the coils of each coil set are electrically connected together bythe magnet wire in an electrical connection pattern, as is generallyshown in FIG. 10.

In accordance with this invention, the first and second auxiliarywinding coil sets AC1 and AC2 and the main winding coil sets MC1 and MC2are inserted in slots S1-S36 of core 5 so that the coils of these coilsets are grouped together in layered fashion in core 5, generally asshown in FIGS. 2 and 3. One coil from each of the first and secondauxiliary winding coil sets and from each of the first and second mainwinding coil sets, as indicated by the coils designated AC1a, MC1a,AC2a, MC2a, form this first layered group of coils. Specifically, coilAC1a is inserted in the slots of the stator core 5, so that its legs Lare received in slots S1 and S3 of the core with its end turns Edisposed out beyond the outer faces of the core. Coil MC1a is insertedin the slots of the core so that the legs are received in slots S2 andS4. The legs of the second auxiliary winding coil set coil AS2a areinserted in slots S3 and S5, and the legs of the last coil of thelayered group, coil MC2a, are inserted in slots S4 and S6 so that theentire layered group of coils extends over slots S1-S6 and spans teethT1-T5.

A second layered group of coils, as indicated by coils AC1b, MC1b, AC2band MC2b is inserted in slots S5-S10 and spans teeth T5-T9.Specifically, the legs L of coil AC1b are inserted in slots S5 and S7,coil MC1b is inserted in slots S6 and S8, coil AC2b is inserted in slotsS7 and S9, and coil MC2b is inserted in slots S8 and S10.

Further in accordance with the present invention, other layered groupsof coils are likewise inserted in slots S1-S36 around bore B of core 5in the same manner as described above for the first two groups. Asillustrated, nine layered groups of coils, AC1a-MC1b through AC1i-MC1iare inserted in the core. It will be understood that the layered groupsof coils overlap one another. It will also be noted that, in accordancewith this invention, only the auxiliary winding coils are inserted incertain of the slots and only the coils of the main windings areinserted in others of the slots. Specifically, in regard to the firstgroup of coils, it will be noted that only the auxiliary winding coilsare inserted in slots S1, S3, S5, etc., while only the main windingcoils are inserted in slots S2, S4, S6, etc. With the various coils ofthe auxiliary and main windings of stator 3 electrically connectedtogether, as shown in FIG. 10, they form the windings W of a slow speed,multiple-pole, induction motor, such as may be particularly well suitedfor use as a ceiling fan motor.

Further in accordance with this invention, the method of the presentinvention generally involves the procedure of inserting the coils of thefirst and second auxiliary winding coils sets AC1 and AC2 and of thefirst and second main winding coil sets MC1 and MC2 in the slots S ofcore 5 generally in the manner described above in layered, overlappinggroups, as discussed above and as shown in FIG. 2. Specifically, themethod of this invention of inserting the coils may be carried out byfirst inserting the coils of the first auxiliary winding coil set AC1 intheir respective slots (e.g., in slots S1 and S3, S5 and S7, S9 and S11,etc.). Then, the coils of the first main winding coil set MC1 areinserted in their respective slots (e.g., in slots S2 and S4, S6 and S8,S10 and S12, etc.). Then, the coils of the second auxiliary winding coilset AC2 are inserted in their respective slots (e.g., in slots S3 andS5, S7 and S9, etc.). Finally, the coils of the second main winding coilset MC2 are inserted in their respective slots (e.g., in slots S4 andS6, S8 and S10, etc.).

It will be particularly noted that by dividing the auxiliary and mainwindings into two coil sets each, and by inserting the coils of thefirst and second coil sets of the auxiliary winding in the same slots,with the coils of the main winding coil sets being interleafed betweenbut not inserted in the same slots, only two relatively small coils needbe inserted in the slots for the auxiliary winding or in the slots forthe main winding, thus permitting the apices or end turns of each of thecoils to be bent to a relatively small radius (as shown in FIG. 6) andthus permitting the size of the end turns E of the windings W to besubstantially reduced from similar prior art motors, such as is shown inFIGS. 4 and 5, which will be described in detail below. A statorassembly 3 made in accordance with this invention has substantially thesame electrical operating characteristics as equivalent prior artconcentric coil motor stator assemblies, such as shown in FIGS. 4 and 5,yet, surprisingly, requires substantially less magnet wire.Additionally, because the end turns E of the windings W have beensubstantially reduced in the stator assembly 3 of the present invention,the requirement of having to lace the end turns so as to hold themagainst movement during operation of the motor has been eliminated, thusagain resulting in significant cost savings.

Referring now to another stator assembly of the present invention, whichis generally indicated by reference character 3' in FIG. 3 and which isfurther illustrated in FIGS. 3 and 7, this other stator assembly of thisinvention will now be described in detail. In contrast to statorassembly 3 shown in FIG. 2, which was earlier described as a concentriccoil stator assembly, stator assembly 3' shown in FIG. 3 is a so-calledskein wound stator assembly. However, this skein wound stator assembly3' is similar to the stator assembly 3 described above in that the coilsof the auxiliary and main winding coil sets are inserted in the statorslots S1'-S36' in layered, overlapping groups. In regard to thefollowing description of stator assembly 3', it will be understood thatparts of stator assembly 3' corresponding to parts of the statorassembly 3 described above have "primed" reference characters so as toindicate corresponding parts having similar functions. The auxiliary andmain windings A' and M' of stator assembly 3' are also divided intofirst and second auxiliary winding coil sets AC1' and AC2', and intofirst and second main winding coil sets MC1' and MC2'. However, incontradistinction to the concentric coil windings described above inregard to stator assembly 3, the windings W' in stator assembly 3' areskein windings, generally as shown in FIG. 7.

Referring now to FIG. 14, a skein wound coil set (e.g., coil set AC1)for either the first or second auxiliary or main winding coil sets ofstator assembly 3', as illustrated in FIG. 3, is shown in plan formafter being formed on a skein coil former, such as is disclosed in theco-assigned and co-pending U.S. Pat. No. 4,357,968, issued to Vernone E.Keiffer, which is incorporated by reference. Specifically, each of thecoil sets for the auxiliary and main windings constitute a single coilor skein of wire having a multiplicity of individual turns of wire whichare formed to produce a petalled, serpentine coil form with a series ofinwardly directing apices APi1-Api9 and a plurality of outwardlydirected apices APo1-APo9 with generally straight coil sections or legsL' between the inner and outer apieces E'. Thus, each coil C of theskein wound coil sets comprises one outer and one inner apices E'together with two straight coil sections L'.

Referring now to FIGS. 3 and 7, the insertion of the auxiliary and mainwinding coil sets AC1', MC1', AC2' and MC2' in core 5' will now bedescribed in detail. It will be understood, however, that a coilinsertion method described below in which the four coil sets aredescribed to be inserted one after the other is a possible insertionmethod, but that another method, also described below, in which all fourcoil sets are simultaneously inserted in the core is preferred. However,the first-described method is useful in inserting coils where the slotfill is high. It will also be understood that the first method may alsobe used to insert coils C for stator 3 described earlier.

Specifically, in regard to FIG. 3, the first method of inserting thecoil sets in the core involves the insertion of the first auxiliarywinding coil set AC1 in core 5'. It will be understood that all of thelegs of the skein wound coil set AC1' may be inserted substantiallysimultaneously into the stator slots S' of core 5' by means of an axialcoil inserter machine, as generally indicated at 201 in FIG. 16, such asgenerally known to those skilled in the art. As shown in FIG. 7, a legL' of coil AC1a' is inserted in slot S1' with the inner apex APi1disposed on one side of core 5' and with the outer apex APo1 disposed onthe opposite side of the core. The next adjacent leg L' of the firstauxiliary winding coil set AC1' is inserted in slot S3' with the outerapex APo2 disposed on the same outside face of core 5' as the otherouter apex APo1. The remaining legs L' of the first auxiliary coil AC1'set are inserted in alternate core slots (e.g., S5', S7', S9' etc.).

Further in accordance with this invention, after insertion of the firstauxiliary winding coil set, the first main winding coils set MC1' isinserted in the slots of core 5' in a manner similar to the firstauxiliary winding coil set described earlier. As shown in FIG. 3, thefirst leg L' of the first coil MC1a' is inserted in slot S2' and thenthe next other leg is inserted in alternate slots. The other coilsconstituting the first layered group of coils (i.e., coils AC2a' andMC2a') are respectively inserted in slots S3' and S5' and in slots S4'and S6'.

Still further in accordance with this invention, the second auxiliarywinding coil set AC2' is inserted in the slots of the stator such thatthe legs of the second auxiliary winding coil set are received in slotsS3', S5', . . . so that the odd numbered slots (e.g., slots S1', S3',S5' . . . ) each have one leg L' of each of the first and secondauxiliary winding coil sets AC1' and AC2' inserted therein. Stillfurther, the second main winding coil set MC2' is inserted in the evennumbered slots starting at slot S4' so that each of the even numberedslots S4', S6', S8' . . . has one leg of each of the coil sets MC1' andMC2' of the main winding inserted therein. Thus, the coils of each ofthe main and auxiliary winding coil sets are grouped in layered sets orgroups with each set or group including, for example, coils AC1a',MC1a', AC2a', and MC2a'. Once the main and auxiliary winding coil setshave been inserted in core 5, the individual coil sets and the coilstherein are electrically interconnected with one another, as is shown inFIG. 14, so that the resulting stator assembly 3' may be utilized in amultiple-pole induction motor.

Stator assembly 3' results in even more compactness (and hence materialand weight savings) then does stator assembly 3 heretofore described.This is realized in part because of the ease with which the skein woundmain and auxiliary winding coil sets AC1', AC2' and MC1', MC2' may beinserted in core 5.

Main and auxiliary winding coil sets MC1, MC2 and AC1, AC2 of statorassembly 3 are preferably wound on conventional coil winding apparatus,such as is commercially available from Industra Products, Inc. of FortWayne, Ind., or on a coil winding machine, such as shown in theco-assigned U.S. Pat. No. 3,714,973 to Kieffer et al which isincorporated by reference.

Further, a coil transfer tool, as indicated generally at 101 in FIG. 15,may be used to transfer the coils of one of the coil sets for eitherstator 3 or 3' from the coil winder to the blades of axial coilinserting machine 201. One such coil inserting machine is disclosed inU.S. Pat. No. 3,324,536 issued to D. E. Hill, June 13, 1967. Such coilinserting machines are also commercially available from IndustraProducts, Inc. A further example of a coil insertion device which may beused to insert the coil sets of the stator assemblies 3 or 3' in thecores 5 or 5' of the present invention is shown in the co-assigned U.S.Pat. No. 3,748,714 to Kieffer, which is incorporated by reference. Aportion of the Kieffer coil inserting machine is shown in FIG. 16 toinclude wedge guide members 203 attached to a base 205 which in turn issupported on a platform or table 207. Further, a plurality of blades 209and cooperative strippers (not shown) are provided. Selected blades areconnected by plates (not shown) in such manner as to define slotsbetween holes 209 for receiving the coils constituting the coil sets.Stator core 5 is positioned above blades 209 and an actuating mechanismis provided below table 207 for forceably moving the strippers so thatwith the coils of the coil set(s) placed on the blades, the strippersforce the coils upwardly thereby to insert the coils in preselectedslots S of the core. For a further description of the construction andoperation of the coil inserting machine, reference may be made to U.S.Pat. No. 3,748,714.

As shown in FIG. 15, transfer tool 101 includes a base 103 and aplurality of elongate, cantilevered fingers F extending axially from thebase, these fingers being spaced apart a distance sufficient toaccommodate a leg L of a coil C therebetween. As shown in FIG. 15, tool101 has eighteen fingers F1-F18 and the outer end of each of the fingersis so structured such that the placement of the coils on the tool andthe insertion of the coils in the slots of core 3 or 3' is facilitated.Preferably, transfer tool 101 is of a suitable synthetic resin.

With a coil set, for example AC1, on transfer tool 101, as shown in FIG.15, the transfer tool is installed on an axial coil inserting machineand the coil set is transferred from the transfer tool 101 to theinserting blades 209 of the inserting machine 201 in the mannerdescribed in the above-mentioned U.S. Pat. No. 3,714,973 to Keiffer.

After the first coil set or coil layer (e.g., the first auxiliarywinding coil set AC1) has been inserted in core 3, as shown in FIG. 2,the next coil layer to be inserted (i.e., coil set MC1) is transferredfrom the coil winding machine to the axial inserting machine on itsrespective transfer tool 101 and is installed on the inserting blades ofthe inserting machine. However, upon inserting the second coil layer,the second coil set MC1 is indexed or rotated relative to stator core 3and the inserting blades so that the first leg of the first coil MC1a ofthis second coil layer is now in position to be inserted in itsrespective slot S2 and so that the other legs of the other coils of thissecond coil layer are in register with their respective core slots S4,S6, S8, . . . .

Further, upon inserting the third and fourth coil layers (i.e., coilwinding sets AC2 and MC2), these other coil sets are indexed so that thefirst leg of the first coil AC2a of the third coil layer AC2 is insertedin slot S3 and so that the next adjacent legs of the third coil layerare inserted in slots S5, S7, S9, . . . , and so that the first coil legof the first coil MC2a of the fourth coil layer MC2 is inserted in slotS4 and so that the remaining legs of the fourth coil layer arerespectively inserted in slots S6, S8, S10, . . . . In this manner, coilsets AC1, MC1, AC2, MC2 may be readily inserted in core 5 so as to formthe above-described layered groups of coils.

Likewise, the skein wound coil sets AC1', MC1', AC2' and MC2' of stator3' of this invention may be readily inserted in core 5'. Morespecifically, the first coil set AC1' carried by tool 101 is transferredto the inserting blades of an axial coil inserting machine. Core 5' isthen positioned above the inserting blades and the inserting machine isoperated in the conventional manner so as to insert the first coil setAC1' in its above-stated slots S1', S3', S5', . . . , as shown in FIG.3, thereby to form a first coil layer. Then the next coil set is indexedrelative to the inserting blades as it is installed on the insertingblades from a respective transfer tool 101, and the inserting machine isactuated so as to effect the installation of the legs L' of the secondcoil set MC1' in slots S2', S4', S6', . . . , to form a second coillayer. Likewise, the third and fourth coil sets AC2' and MC2' areindexed on the blades and are inserted in their respective slots, asshown in FIG. 3, so as to respectively form third and fourth coillayers.

It will be understood that insulators 23 and wedges 25 are automaticallyformed and inserted in the slots by methods well-known to those skilledin the art.

Further in accordance with this invention, a second and preferred methodof inserting coil sets AC1, MC1, AC2 and MC2 in core 5 will now bedescribed. First, coil set AC1 is transferred on its respective transfertool 101 to the inserting blades 209 of coil inserting machine 201 in amanner well-known to those skilled in the art so that the legs L of thefirst coil set are in position to be inserted in their intended slots(i.e., slots S1, S3, S5, . . . ) of core 5. Then, the next coil set MC1is transferred on its respective transfer tool to the coil insertionmachine and is installed on inserting blades 209 so that the legs ofthis second coil set are in position to be inserted in their intendedslots (i.e., in slots S2, S4, S6, . . . ) of the core. It will be noted,however, that the coils of coil set AC1 and the coils of coil set MC1are rotated or angularly offset relative to one another on blades 209one slot (i.e., about 10°). Similarly, the third and fourth coil setsAC2 and MC2 are installed on the inserting blades so that the legs ofcoil set AC2 are in register with their intended slots S3, S5, S7, . . .and with slots S4, S6, S8, . . . , respectively.

With core 5 in position above the inserting blades 209, generally asshown in FIG. 16, and with all four coils sets installed on the bladesas described above, the coil inserting machine is actuated and all fourcoil sets are substantially simultaneously inserted in their respectiveslots.

In regard to the stator assemblies 3 and 3' of the present inventionheretofore described and shown in FIGS. 2 and 3, the auxiliary coilwinding sets were described to be the first windings to be in thestator. It will be understood, however, that this is but one preferredembodiment of the insertion pattern in accordance with the apparatus andmethod of the present invention. It will be further understood thatinstead of placing the auxiliary coil winding set first, one of the mainwinding coil sets may be first placed in the slots of the core. Itshould be noted, however, that both the method and apparatus of thepresent invention contemplate that the various coils of the coil sets begrouped together in layered groups similar in construction to those setout above.

Referring now to FIGS. 4 and 5, two prior art stator assemblies formultiple-pole induction motors suitable for use as ceiling fan motorsare disclosed. These prior art motors will be described in detail, sothat their construction and operation may be compared with the statorassemblies 3 and 3' of the present invention, as described earlier.

Referring now to FIG. 4, a prior art, concentric coil stator assembly isshown. It will be understood that parts of the prior art stator coilassembly having a similar construction and operation as thecorresponding parts of stator assemblies 3 and 3' of the presentinvention heretofore described have corresponding reference charactersand thus will not be described in detail. Specifically, the windings Wof this prior art stator assembly, as shown in FIG. 4, comprise anauxiliary winding AW and a main winding MW which are each formed of aplurality of individual, concentric coils. Both the auxiliary and themain windings each include nine individual coils which are inserted intorespective slots S of the stator assembly. As shown in FIG. 4, the firstcoil AW1 of the auxiliary winding AW is inserted in slots S1 and S3 sothat it spans teeth T1 and T2. The next adjacent coils AW2 of theauxiliary winding is inserted in slots S5 and S7 so that it spans teethT5 and T6. The remaining coils for the auxiliary windings are theninserted in their respective slots around stator core 5 with the legs ofthe auxiliary winding coils being received in slots S9, S11, S13 . . . ,and with an even numbered slots S4, S8, S12 . . . between each of theauxiliary coils. The first main winding coil MW1 is inserted in slots S4and S6 and the next main winding coil MW2 is inserted in slots S8 andS10. The remaining main winding coils are inserted in the even-numberedslots with one odd-numbered slot S3, S7, S11, . . . between each mainwinding coil. It will be noted that each stator slot has only one leg ofone coil (i.e., either a leg of an auxiliary winding coil or a mainwinding coil) inserted therein. Each coil has, for example, a relativelylarge number of turns (e.g., 184 turns for the main coils and 330 forthe auxiliary coils) of a specified wire thickness (e.g., #24 wire forthe main coil and #27 wire for the auxiliary coil). Because these singlecoils for both the main and the auxiliary windings are relatively thick,they must have relatively large end turns E. Because these end turns arerelatively large, the end turns of the windings must be laced togetherwith suitable textile fiber lacing material LA thereby to physicallyhold the end turns against movement relative to one another and to holdthe end turns in desired position during operation of the motor.

The stator assembly shown in FIG. 4 is electrically connected so thatthe individual coils of both the auxiliary and main windings AW and MWare series connected to one another in the manner shown by the wiringdiagram in FIG. 12.

Referring now to FIG. 5, another embodiment of a stator assembly for amultiple-pole induction motor is shown. Like the prior art statorassembly heretofore described and shown in FIG. 4, this prior art statorassembly comprises a main winding MW' and an auxiliary winding AW'.Here, however, each of the coils for the main winding and the auxiliarywinding (i.e., coils MW1' and AW1') have been divided into respectivepairs of coils MW1a, MW1b and AW1a, AW1b. Each main winding coil MW1a,MW1b may have 92 turns of #24 magnet wire therein, and each auxiliarycoil AW1a, AW1b may have 165 turns of #27 magnet wire. As shown in FIG.5, the first coil AW1a the first pair of coils AW1a, AW1b has its firstleg L inserted in slot S1 and its other leg inserted in slot S3. Thefirst leg of the second coil AW1b is also inserted in slot S3 and theother leg of the second coil is inserted in slot S5. Thus, the effectivespan of the first pair of auxiliary coils AW1a, AW1b of the statorassembly shown in FIG. 5 is from slot S1 to slot S5.

In a comparison of the stator assemblies shown in FIGS. 4 and 5, it willbe seen that the effective span of the coils (i.e., coil AW1 in FIG. 4and the pair of coils AW1a, AW1b in FIG. 5) of the auxiliary and mainwindings of the prior art stator assembly spans four teeth and theelectrical characteristics of the motor are generally similar to oneanother. It will be noted that each of the coils of the windings of thestator assembly of FIG. 5 has half as many turns of wire than windingsof the stator assembly of FIG. 4, and the end turns of the coils of thestator assembly of FIG. 5 may be formed to be on a tighter radius ofcurvature and thus the size of the end turns is appreciably decreased.For example, the amount of magnet wire required for the main andauxiliary windings of the stator assembly shown in FIG. 5 isapproximately 5 percent less than amount of magnet wire required for thestator assembly shown in FIG. 4, with these two stator assemblies havingessentially identical electrical characteristics. This does represent areduction in cost. However, the prior art stator assembly shown in FIG.5 nevertheless represents a considerable cost to manufacture and,because of the requirement of having to insert two legs of the coils incommon slots, it is difficult to insert the coils in the slots, and thusthis winding pattern may not be used for certain motor designs.

EXAMPLE

Stator assemblies 3 and 3' made in accordance with the method andapparatus of the present invention, such as illustrated in FIGS. 2 and3, were constructed so as to have substantially identical electricalcharacteristics and were tested and the results compared. The cores 5and 5' for stator assemblies 3 and 3' were constructed from 42laminations of suitable ferromagnetic sheet-material having a thicknessof 0.0295 inches (0.75 mm.). The bore B of the stator cores was 3.5inches (8.9 cm.), and 36 slots S were provided. Each of the coils forthe first and second auxiliary winding coil sets were wound with 165turns of #28 wire, and each of the coils of the first and second mainwinding coil sets were wound with 92 turns of #24 wire. Stator assembly3 shown in FIG. 2 had a wire weight of approximately 1.57 lbs. (0.71kg.) and the wire weight of stator assembly 3' was essentially the same.When these stator assemblies were assembled in a motor in the mannergenerally shown in FIG. 1 with a suitable rotor assembly 13 installed inbore B, the motors produced 20.6 watts of power while consuming 110watts of electrical power and while operating at a speed of 200 RPM.

As a comparison, two prior art stator assemblies generally as shown inFIGS. 4 and 5, were tested against the two stator assemblies 3 and 3' ofthe present invention. The prior art stator assembly generally shown inFIG. 4 consisted of a core made of 42 laminations of ferromagneticsheet-material with each lamination having a thickness of 0.0295 inches(0.75 mm.) and having a bore B of 3.5 inches (8.9 cm.). The auxiliarywinding of the stator assembly shown in FIG. 4 has nine coils of magnetwire, with each coil having 330 turns of #27 wire, while the mainwinding consisted of nine individual coils of #24 magnet wire and having184 turns This prior art stator assembly had a wire weight ofapproximately 2.02 lbs. (0.91 kg.), and drew 112.5 watts of electricalpower to produce 20.6 watts of work while operated at 200 R.P.M.

From a review of the stator assemblies 3 and 3' of the present inventionas compared with the prior art stator assemblies, it can be seen thatthe wire weight of stator assembly 3 or 3' of the present invention isabout 22% less than that of the prior art stator assembly shown in FIG.4. Yet, surprisingly, the stator assemblies 3 and 3' of the presentinvention have somewhat improved electrical characteristics over theabove-described prior art stator assemblies.

Because the stator assemblies 3 and 3' of the present invention usesignificantly less magnet wire than the stator assemblies heretoforeutilized with prior art multiple-pole electric induction motors havingsimilar electrical characteristics, it will be appreciated that thestator assemblies made in accordance with this invention represent asignificant step forward in the motor art and result in appreciable costsavings in the manufacture of motors utilizing these stator assemblies.

While the stator assemblies and methods of the present invention haveheretofore been described in conjunction with the fabrication of 18 poleinduction motors intended for use as ceiling fan motors, those skilledin the art will appreciate that the stator assemblies and methods of thepresent invention may be utilized to construct other dynamoelectricmachines for other applications having any number of desired poles.

In view of the above, it will be seen that the several objects andfeatures of this invention are achieved and other advantageous resultsobtained.

As various changes could be made in the above constructions and methodswithout departing from the scope of the invention, it is intended thatall matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A stator for a multiple-pole dynamoelectricmachine comprising a core of a stack of laminations of suitableferromagnetic material, said core having a central bore extendingtherethrough and a plurality of blind slots extending radially outwardlyfrom said bore, said slots being substantially equally angularly spacedabout said bore, an auxiliary winding divided into a first auxiliarywinding coil set and a second auxiliary winding coil set, and a mainwinding divided into a first main winding coil set and a second mainwinding coil set, each of said coil sets being constituted by arespective skein of a suitable magnet wire of petalled, serpentine shapedefining a plurality of coils with each coil having a multiplicity ofturns of said magnet wire therein and with each coil having a first anda second end turn and a pair of straight coil sections between each ofthe end turns, said core having a first straight coil section of a firstcoil of a first of said coil sets inserted in a first slot of said coreand the next straight coil section of said first coil of said first coilset being inserted in the third slot of said core, the remainder of thestraight coil sections of said first coil set being inserted in thefifth, seventh, . . . , and next to last slots of said core, saidstraight coil sections of a second coil set being inserted in saidsecond, fourth, sixth, . . . , and last slots of said core, saidstraight coil sections of a third coil set being inserted in the third,fifth, seventh, . . . , and first slots of said core, and the coilsections of a fourth coil set being inserted in the fourth, sixth,eighth, . . . , and second slots of said core, said coil sets beingelectrically connected for operation of said dynamoelectric machine. 2.A stator for a multiple-pole dynamoelectric machine comprising a core ofa stack of laminations of suitable ferromagnetic material, said corehaving a central bore extending therethrough and a plurality of blindslots extending radially outwardly from said bore, said slots beingsubstantially equally angularly spaced about said bore, a auxiliaryfirst winding divided into a first coil set and a second coil set, and amain second winding divided into a first coil set and a second coil set,each of said coil sets being constituted by a respective skein ofsuitable magnet wire of petalled, serpentine shape defining a pluralityof coils with each coil having a multiplicity of turns of said magnetwire therein and with each coil having a first and a second end turn anda pair of straight coil sections between each of the end turns, saidcore having a first straight coil section of a first coil of a first ofsaid coil sets inserted in a first slot of said core and the nextstraight coil section of said first coil of said first coil set beinginserted in the third slot of said core, the remainder of the straightcoil sections of said first coil set being inserted in the fifth,seventh, . . . , and next to last slots of said core, said coil sectionsof a second coil set being inserted in said second, fourth, sixth, . . ., and last slots of said core, said coil sections of a third coil setbeing inserted in the third, fifth, seventh, . . . , and first slots ofsaid core, and the coil sections of a fourth coil set being inserted inthe fourth, sixth, eighth, . . . , and second slots of said core, saidcoil sets being electrically connected for operation of saiddynamoelectric machine.
 3. A stator for a multiple-pole dynamoelectricmachine comprising a core of a stack of laminations of suitableferromagnetic material, said core having a central bore extendingtherethrough and a plurality of blind slots extending radially outwardlyfrom said bore, said slots being substantially equally angularly spacedabout said bore, at least a first winding and a second winding, each ofsaid windings comprising a respective skein of a suitable magnet wire ofpetalled, serpentine shape defining a plurality of coils, with each ofsaid coils having a multiplicity of turns of said magnet wire, at leastone straight section for insertion into said slots of said core, and anend turn interconnecting said straight sections out beyond the end facesof said core, said first and second windings having means for decreasingthe size of said end turns, this last-said means comprising a divisionof said first and second windings into first and second coil sets forsaid first and second windings, said core having a first straight coilsection of a first coil of said first coil sets inserted into a firstslot of said core, and the next straight coil section of said first coilof said first coil set being inserted into the third slot of said core,the remainder of the straight coil sections of said first coil set beinginserted into the fifth, seventh, ninth, . . . , and the next to lastslots of said core, said coil sections of a second coil set beinginserted into the second, fourth, sixth, . . . , and last slots of saidcore, said coil sections of a third coil set being inserted in thethird, fifth, seventh, . . . , and the first slots of said core, and thecoil sections of a fourth coil set being inserted in the fourth, sixth,eighth, . . . , and the second slots of said core, the first coils ofeach of said coil sets constituting a first physical pole of saidstator, the second coils of each of said coil sets constituting a secondphysical pole of said stator, . . . , such that there is a physical polein said stator for each coil in said winding, said coil sets beingelectrically connected for operation of said dynamoelectric machine. 4.A stator for a multiple-pole dynamoelectric machine comprising a core ofa stack of laminations of suitable ferromagnetic material, said corehaving a central bore extending therethrough and a plurality of blindslots extending radially outwardly from said bore, said slots beingsubstantially equally angularly spaced about said bore, an auxiliarywinding divided into a first auxiliary winding coil set and a secondauxiliary winding coil set, and a main winding comprising at least onemain winding coil set, each of said coil sets being constituted by arespective skein of a suitable magnet wire of petalled, serpentine shapedefining a plurality of coils, with each coil having a multiplicity ofturns of said magnet wire therein, and with each coil having a first anda second end turn and a pair of straight coil sections between each ofthe end turns, said core having a first straight coil section of a firstcoil of a first of said coil sets inserted in a first slot of said core,and the next straight coil section of said first coil of said first coilset of said auxiliary winding being inserted in a first slot of saidcore, and the next straight coil section of said first coil of saidfirst coil set of said auxiliary winding being inserted in the thirdslot of said core, the remainder of the straight coil sections of saidfirst coil set of said auxiliary winding being inserted in the fifth,seventh, . . . , and next to last slots of said core, said straight coilsections of said main winding coil set being inserted in said second,fourth, sixth, . . . , and last slots of said core, said straight coilsections of said main winding coil set being inserted in said second,fourth, sixth, . . . , and last slots of said core, and said straightcoil sections of said second coil set of said auxiliary winding beinginserted in the third, fifth, seventh, . . . , and first slots of saidcore, the first coils of each of said coil sets constituting a firstphysical pole of said stator, the second coils of each of said coil setsconstituting a second pole of said stator, . . . , such that there is aphysical pole in said stator for each coil and each of said windings,said coil sets being electrically connected for operation of saiddynomelectric machine.
 5. A stator for a multiple-pole dynamoelectricmachine comprising a core of a stack of laminations of suitableferromagnetic material, said core having a central bore extendingtherethrough and a plurality of blind slots extending radially outwardlyfrom said bore, said slots being substantially equally angularly spacedabout said bore, a main winding divided into a first main winding coilset and a second main winding coil set, and an auxiliary windingcomprising at least one auxiliary winding coil set, each of said coilsets being constituted by a respective skein of a suitable magnet wireof petalled, serpentine shape defining a plurality of coils, with eachcoil having a multiplicity of turns of said magnet wire therein, andwith each coil having a first and a second end turn and a pair ofstraight coil sections between each of the end turns, said core having afirst straight coil section of a first coil of a first of said coil setsinserted in a first slot of said core, and the next straight coilsection of said first coil of said first coil set of said auxiliarywinding being inserted in a first slot of said core, and the nextstraight coil section of said first coil of said first coil set of asaid main winding being inserted in the third slot of said core, theremainder of the straight coil sections of said first coil set of saidmain winding being inserted in the fifth, seventh, . . . , and next tolast slots of said core, said straight coil sections of said auxiliarywinding coil set being inserted in said second, fourth, sixth, . . . ,and last slots of said core, said straight coil sections of saidauxiliary winding coil set being inserted in said second, fourth, sixth,. . . , and last slots of said core, and said straight coil sections ofsaid second coil set of said main winding being inserted in the third,fifth, seventh, . . . , and first slots of said core, the first coils ofeach of said coil sets constituting a first physical pole of saidstator, the second coils of each of said coil sets constituting a secondpole of said stator, . . . , such that there is a physical pole in saidstator for each coil and each of said windings, said coil sets beingelectrically connected for operation of said dynamoelectric machine.